1. Field of the Invention
The present invention relates to an ink jet head and a method of manufacturing the ink jet head.
2. Description of the Related Art
A certain type ink jet head is manufactured by fixing a passage unit and an actuator unit.
The passage unit is provided with at least one common passage, a plurality of branching passages, a plurality of pressure chambers, and a plurality of nozzles. Ink supplied from the exterior of the passage unit is received in the common passage. The plurality of branching passages branch from the common passage. Each of the pressure chambers is formed part-way along one corresponding branching passage. Each of the nozzles communicates with an end part of one corresponding branching passage, and opens to the exterior of the passage unit. There is an equal number of branching passages, pressure chambers and nozzles.
The passage unit is composed of a stack of a plurality of metal plates. Penetrating holes, grooves, etc., are formed in each of the metal plates to be stacked. The common passage, branching passages, pressure chambers, and nozzles are formed by stacking the metal plates.
The actuator unit is provided with a plurality of actuators. There is an equal number of actuators and pressure chambers. Each of the actuators can be controlled independently.
The actuator unit is fixed to a top metal plate of the passage unit. The positions in which the actuators of the actuator unit are disposed, and the positions in which the pressure chambers of the passage unit are disposed are adjusted such that each actuator is coupled with a corresponding pressure chamber when the actuator unit is fixed to the top metal plate of the passage unit.
When one actuator is activated, the pressure increases within the pressure chamber that corresponds thereto, and ink is discharged from the nozzle communicating with this pressure chamber. The nozzle from which the ink will be discharged can be chosen by choosing which actuator to activate. The timing at which the ink will be discharged from the nozzle can be chosen by choosing the timing at which the actuator will be activated.
In order to obtain the above phenomenon, the actuator and the corresponding pressure chamber must have a positional relationship such that, when the actuator unit is fixed to the top metal plate of the passage unit, this positional relationship allows the actuator to increase the pressure within the corresponding pressure chamber when the actuator is activated.
One type of passage unit has holes formed in its top face. Each of holes has a bottom. When the actuator unit is fixed to the top face of the passage unit, each of the holes is covered by the actuator unit. These cavities form the pressure chambers. A positional relationship can be obtained such that, when an actuator is selected and activated, the pressure is increased within the pressure chamber corresponding to that actuator. With this type of passage unit, the top metal plate is provided with a plurality of penetrating holes, for forming pressure chambers.
In another type of passage unit, holes that have a bottom and form the pressure chambers are covered by a vibrating plate. The vibrating plate is a thin plate that flexibly deforms. In this case, as well, a positional relationship can be obtained such that, when an actuator is selected and activated, the pressure is increased within the pressure chamber corresponding to that actuator. With this type of passage unit, the top metal plate of the passage unit is the vibrating plate and has a flat surface.
When the ink jet head is to be manufactured, the passage unit and the actuator unit are manufactured separately. The passage unit and the actuator unit are then fixed.
The passage unit is manufactured by stacking the plurality of metal plates, as described above, and then bonding together the stacked metal plates. In order to do this, a stack of all metal plates that comprises the passage unit is provided, and this stack is heated under pressure to bond all the metal plates at one time. When the stacked metal plates are heated under pressure, the metal plates are bonded stably together by metal diffusion bonding. The passage unit can be manufactured efficiently by bonding all the metal plates that comprise the passage unit at one time.